1. The Field of the Invention
This invention pertains to cellular precast blocks or grids for use with or without interconnecting cables as revetment for stabilization of the banks of streams and rivers, levies, river bottoms, shores, ditches, channels, canals and the like and protection from erosion by water waves and currents and/or wind.
2. Description of the Prior Art
The use of precast concrete members, including members joined into a mat or mattress by interconnecting cables or rods, is well known in the art. Such previously known members include precast concrete members with or without cellular structure and members cast around rods or cables utilized for interconnection of members into a mat as well as members cast with tunnels or openings through which connecting means, such as cables or rods, are passed to accomplish interconnection of members into mats.
Known flexible concrete revetment includes an articulated concrete mattress comprising rectangular slabs of concrete interconnected by wires as disclosed by U.S. Pat. Nos. 2,674,856 and 2,876,628. Such revetment permits considerable erosion when cracks appear in slabs and does not accommodate hydrostatic pressure. It also inhibits establishment of vegetative growth and does not encourage sedimentation or provide velocity dissipation of flowing water.
An improved flexible concrete revetment is disclosed by U.S. Pat. No. 3, 597,928, which comprises a flexible liquid-permeable supporting sheet upon which precast concrete blocks, which have vertical drainage openings, are secured in side by side abutting arrangement. In one form of this revetment, the top surface of the blocks has grooves which form castellations on such surface. The improved revetment of U.S. Pat. No. 3,597,928 avoids the erosion following cracking exhibited by earlier flexible concrete revetment, can accommodate hydrostatic pressure, encourage vegetative growth and sedimentation and provide velocity dissipation for flowing water. The revetment disclosed by U.S. Pat. No. 3,597,928, does not, however, provide the novel means for interlocking adjacent rows of grids provided by the present invention nor does it provide for interconnection of concrete grids into a mattress with pins or parallel cables running in a single direction. It further does not provide a highly articulatable mattress of the present invention while maintaining close abutting contact between adjacent grids in the mattress, nor does it provide other desirable features of the present invention more fully described below.
Desirable properties of revetment include provision of revetment members which mechanically interlock to create a highly stable revetment mat with or without use of additional connecting means, which mat can be interconnected with additional connecting means comprising pins or a single series of parallel cables or rods, can be simply and inexpensively manufactured, and will function as intended by resisting displacement of revetment members by hydraulic pressure, will dissipate water flow, retain particulate matter such as soil, backfill or silt deposits and support and encourage vegetative growth. Revetment exhibiting all of these properties has not heretofore been available.
It is therefore an object of the present invention to provide a cellular precast grid adapted for use as revetment, which interlocks with like grid members into a mat with or without utilization of separate connecting means.
It is a further object of the present invention to provide a cellular precast grid adapted for use as revetment which may be produced of concrete or of other moldable or castable materials.
It is a further object of the present invention to provide a revetment mat of interlocking cellular precast grids interconnected with a single series of parallel cables or rods passing through grid members.
It is a further object of the present invention to provide cellular precast grids and revetment mats which can be simply and inexpensively manufactured utilizing conventional precast concrete manufacturing techniques.
Further objects of the invention include provision of revetment grids and mats designed to resist displacement in use by hydraulic pressure while dissipating water flow and retaining particulate matter such as soil backfill or silt deposition.
A further object of the invention is provision of a grid and mat which will support and encourage vegetative growth.
A further object is provision of revetment grids and mats which exhibit a highly pedestrianable surface.
A further object is provision of a revetment mat which is highly articulatable and thus able to accommodate the topographic contours of sites where such mats are installed.
It is a further object of the present invention to provide a versatile cellular precast grid which may be interconnected with cables into revetment mats in a variety of configurations.
It is a further object of the present invention to provide a revetment mat which utilizes a minimum quantity of interconnecting cable.
It is a further object of the present invention to provide a cellular precast grid design which avoids the tendency for defects to occur in the grid during its manufacture.
It is a further object of the present invention to provide cellular precast grids and revetment mats which may be used with or without filter fabric or other flexible liquid-permeable membranes.
It is a further object of the present invention to provide revetment mats which may be interconnected with like mats to provide continous revetment of any desired dimensions.
It is a further object to provide revetment with a low Manning coefficient.
It is a further object of the present invention to provide revetment which facilitates drainage of water through such revetment from top to bottom and into the soil upon which the revetment rests.
It is a further object of the present invention to provide revetment which will reduce or eliminate erosion of soil substrate on which it is used.
Other objects and advantages of the present invention will become apparent during the course of the following summary and description.